1. Field of the Invention
This invention relates to the design of a mobile interface device, and in particular, relates to the design of mobile interface device having a pen-based user interface.
2. Discussion of the Related Art
Mobile data processing devices (MDPD), including such mobile computers popularly known as personal digital assistants (PDAs), are beginning to proliferate. Because portability is an important consideration in an MDPD and because, in many applications, data entry can be performed without a full keyboard, a "pen" or stylus can be used as an input device for these applications of the MDPD. Portability of an MDPD is desirable because it provides the possibility that the user can accomplish in a mobile fashion tasks which would otherwise have to be accomplished at a desktop computer, or a well-equipped portable computer. However, because of the same portability requirement, MDPDs cannot have the same memory and mass storage resources available locally to accomplish many of these tasks.
Because computer tools can be advantageously used in almost all aspects of business, the business environment (e.g. offices) has been changing rapidly. Computer networks and electronic data communication, e.g. electronic mail and sharable databases, have led to more cooperative efforts among workers. In this regard, especially among the "professional" ranks, workers are becoming more "mobile". In fact, for a significant percentage of all office workers, it is believed that a greater portion of the work day is spent not in one's own office but at conferences or at offices of others. At the same time, because the computer has become an essential tool in the office, the need for immediate data access by these workers wherever they are is even greater.
Another trend resulting from the pervasive use of computers in the work place is the need to place in the hands of "fleet" workers direct access to data. Such fleet workers include workers at hospitals, retail stores, and warehouses etc. Such a worker does not usually perform his or her assigned tasks most efficiently behind a computer terminal. However, substantial productivity benefit can be achieved when such a worker is provided access to data. In some instances, e.g. a nurse at an emergency room, useful data can be collecting by the worker at where he or she is located, using an MDPD. In other instances, e.g. a retail clerk requiring access to inventory, data necessary to carry out the worker's job function can be provided to the worker using an MDPD. In the prior art, special-purpose portable independent devices are designed for use in a specific application. Such special purpose devices are not provided general purpose capability. Such devices cannot be adapted for use in dissimilar applications, and are generally limited to use in well-defined repetitive tasks.
For the mobile professional and for the fleet worker, there is an increasing need for a more flexible and sophisticated machine for data access. For these workers, a portable computer, such as a notebook computer, is not a satisfactory solution. In many applications, because of the collaborative nature of work, data are often required to be readily accessible over a computer network. At the same time, data on portable computers are seldom accessible from a computer network and, very frequently, such data are modified copies of some data already existing elsewhere on a computer network, a desktop computer or a workstation. Consequently, the data stored on a portable computer are often inconsistent with the modified copies of the same data on a desktop computer.
Thus, it is desirable to have an MDPD which can be used as a mobile interface to a desktop computer or a computer network, to take advantage of the resources on the desktop computer or computer network, to provide direct access to a database and to eliminate data inconsistency due to multiple copies of data. Further, such a mobile interface should provide a level of performance sufficient to make using such a device indistinguishable from using a terminal connected to the desktop computer using a conventional wired medium.
Clearly, to provide true mobility to such a device, a wireless link to the desktop computer is essential. To date, a number of manufacturers provide remote control software and hardware that allow packetized data to be sent between a host computer and a handheld digitized tablet over a serial link provided either by a modem or an infra-red (IR) wireless circuit. One such software handles the underlying technology-dependent physical communication protocols, but provides a transport level interface which simulates traditional local area network (LAN) or serial data streams. The wireless link is therefore transparent to an application program interfaced to the software.